- [Clusto](https://github.com/clusto/clusto) - Helps you keep track of your inventory, where it is, how it's connected, and provides an abstracted interface for interacting with the elements of the infrastructure.
- [Collins](http://tumblr.github.io/collins/) - At Tumblr, it's the infrastructure source of truth and knowledge.
- [i-doit](http://www.i-doit.org/) - IT Documentation and CMDB.
- [iTop](http://www.combodo.com/itop-193) - Complete ITIL web based service management tool.
- [GLPI](https://www.glpi-project.org/) - Information Resource-Manager with an additional Administration Interface.
- [GLPI](https://www.glpi-project.org/) - Information Resource-Manager with an additional Administration Interface. ([Source Code](https://github.com/glpi-project/glpi))
- [OCS Inventory NG](https://ocsinventory-ng.org/) - Asset management and deployment solution for all devices in your IT Department. ([Source Code](https://github.com/OCSInventory-NG)) `GPL-2.0``PHP/Perl`
- [OPSI](http://www.opsi.org) - Hardware and software inventory, client management, deployment, and patching for Linux and Windows. ([Source Code](https://github.com/opsi-org/)) `GPL-3.0/AGPL-3.0``OVF/Python`
- [RackTables](http://racktables.org/) - Datacenter and server room asset management like document hardware assets, network addresses, space in racks, networks configuration. ([Source Code](https://github.com/RackTables/racktables), [Demo](https://www.racktables.org/demo.php)) `GPL-2.0``PHP`
- [Claws Mail](http://www.claws-mail.org/) - Old school email client (and news reader), based on GTK+.
- [ImapSync](http://imapsync.lamiral.info/) – Simple IMAP migration tool for copying mailboxes to other servers.
- [Mutt](http://www.mutt.org/) - Small but very powerful text-based mail client.
- [Nylas Mail](https://www.nylas.com/nylas-mail/) - Extensible mail client.
- [Sylpheed](http://sylpheed.sraoss.jp/en/) – Still developed predecessor to Claws Mail, lightweight mail client.
- [Thunderbird](https://www.mozilla.org/de/thunderbird/) - Free email application that's easy to set up and customize.
- [Claws Mail](http://www.claws-mail.org/) - Old school email client (and news reader), based on GTK+. ([Source Code](https://git.claws-mail.org/?p=claws.git;a=tree))
- [ImapSync](http://imapsync.lamiral.info/) – Simple IMAP migration tool for copying mailboxes to other servers. ([Source Code](https://github.com/imapsync/imapsync))
- [Mutt](http://www.mutt.org/) - Small but very powerful text-based mail client. ([Source Code](https://gitlab.com/muttmua/mutt))
- [Sylpheed](http://sylpheed.sraoss.jp/en/) – Still developed predecessor to Claws Mail, lightweight mail client. ([Source Code](https://github.com/sylpheed-mail/sylpheed))
- [Thunderbird](https://www.thunderbird.net/) - Free email application that's easy to set up and customize. ([Source Code](https://hg.mozilla.org/comm-central/file))
- [GNS3](https://www.gns3.com/) - Graphical network simulator that provides a variety of virtual appliances - ([Source Code](https://github.com/GNS3/gns3-gui/), [Documentation](https://docs.gns3.com/)) - `GPLv3`
- [Oxidized](https://github.com/ytti/oxidized) - A modern take on network device configuration monitoring with web interface and GIT storage.
- [phpIPAM](http://phpipam.net/) - Open source IP address management with [PowerDNS](https://www.powerdns.com/) integration.
- [RANCID](http://www.shrubbery.net/rancid/) - Monitors network device's configuration and maintain history of changes.
- [rConfig](http://www.rconfig.com/) - Another network device configuration management tool.
- [trigger](https://github.com/trigger/trigger) - Robust network automation toolkit written in Python.
- [GNS3](https://www.gns3.com/) - Graphical network simulator that provides a variety of virtual appliances. ([Source Code](https://github.com/GNS3/gns3-gui/)) `GPL-3.0``Python`
- [Oxidized](https://github.com/ytti/oxidized) - A modern take on network device configuration monitoring with web interface and GIT storage. `Apache-2.0``Ruby`
- [phpIPAM](http://phpipam.net/) - Open source IP address management with PowerDNS integration. ([Source Code](https://github.com/phpipam/phpipam)) `GPL-3.0``PHP`
- [RANCID](http://www.shrubbery.net/rancid/) - Monitors network device's configuration and maintain history of changes. ([Source Code](https://github.com/haussli/rancid)) `BSD-3-Clause``Perl/Shell`